Low Molecular Weight Phenolic Compounds Research Articles

Thermal Stability of Highly Filled Cellulosic Biocomposites Based on Ethylene–Vinyl Acetate Copolymer

The effect of plant-based fillers on thermal resistance in highly filled biocomposites based on ethylene–vinyl acetate copolymer (EVA) was studied. Wood flour and microcrystalline cellulose were used as fillers. It was shown that the introduction of microcrystalline cellulose into EVA did not affect the thermal stability of the polymer matrix. In contrast, the introduction of wood flour into EVA led to a significant increase in the thermal stability of the entire biocomposite. Oxidation induction time increased from 0 (pure EVA) to 73 min (EVA + wood flour biocomposites). The low-molecular weight phenolic compounds contained in wood flour are likely able to diffuse into the polymer matrix, exerting a stabilizing effect. The discovered stabilizing effect is a positive development for expanding the possibilities of technological processing of biocomposites, including multiple processing.

Impact of pre- and post-fermentation fining with polyvinylpolypyrrolidone on the chemical stability and aromatic profile of Viognier wine.

Polyvinylpolypyrrolidone (PVPP) is a synthetic, insoluble polymer that can be added to white wines to improve the chemical stability of the final product by precipitating unstable low molecular weight phenolic compounds responsible for visual defects and undesirable flavor characteristics (e.g., excessive bitterness and/or astringency). The objective of this study was to characterize the effects of PVPP on the quality characteristics of Viognier wine when added pre- or post-fermentation as compared to an untreated control wine. Both PVPP-treated wines contained significantly lower concentrations of monomeric phenolics and browning pigments than the control wine (p≤0.05). The addition of PVPP prior to fermentation conferred protection against oxidation of the wine as measured by acetaldehyde concentration (p≤0.05). Analysis of the volatile aroma profile of each wine by headspace solid phase microextraction gas chromatographymass spectrometry (HS-SPME-GC-MS)revealed that the overarching aroma profiles of the PVPP-treated wines were significantly different from the control wine, but there was no difference between wines treated with PVPP pre-fermentation versus those treated post-fermentation. Specifically, statistically significant differences were observed in 9 of the 22 quantified aroma compounds, including those notably associated with the "stone fruit" aroma of Viognier. A negative correlation was identified between aroma compound concentration removal and the hydrophobicity of each compound, suggesting that the observed differences in aroma may be due to adsorption of aroma compounds by PVPP. The findings from this study present risks and benefits to wine quality upon treatment with PVPP at commercially recommended levels, and provide potentially valuable information for industrial wine producers.

The efficacy and safety of a fixed-dose combination of apocynin and paeonol, APPA, in symptomatic knee OA: A double-blind, randomized, placebo-controlled, clinical trial

ObjectiveApocynin (AP) and paeonol (PA) are low molecular weight phenolic compounds with a broad array of anti-inflammatory and immunoregulatory effects. This study assessed of a fixed-dose combination of APPA in people with symptomatic knee osteoarthritis (OA). MethodsA multi-center, randomized, placebo-controlled, double-blind phase 2a trial enrolled participants with radiographic knee OA (Kellgren-Lawrence, KL, grades 2-3) and pain ≥40/100 on WOMAC pain subscale, and evaluated the efficacy and safety of oral APPA over a 28-day period. APPA 800 mg or matching placebo was administered twice daily in a 1:1 ratio. Post-hoc analyses explored the response to APPA in sub-groups with more severe pain and structural severity. ResultsThe two groups were comparable at baseline; 152 subjects were enrolled and 148 completed the trial. There was no statistically significant difference between groups with respect to the primary outcome, WOMAC pain (mean difference between groups was -0.89, 95 % CI: -5.62, 3.84, p=0.71), nor WOMAC function or WOMAC total. However, predefined subgroup analyses of subjects with symptoms compatible with neuroplastic/neuropathic pain features showed a statistically significant effect of APPA compared to placebo. Adverse events (mainly gastrointestinal) were mild to moderate. ConclusionTreatment with APPA 800 mg twice daily for 28 days in subjects with symptomatic knee OA was not associated with significant symptom improvement compared to placebo. The treatment was well-tolerated and safe. While the study was not powered for such analysis, pre-planned subgroup analyses showed a significant effect of APPA in subjects with neuroplastic pain/severe OA, indicating that further research in the effects of APPA in appropriate patients is warranted.

Synchronic shifts in phenolic compounds and fungal communities during litter decomposition in boreal forests

Phenolic compounds in plant litter influence decomposition process both directly by their own degree of decomposability and indirectly by affecting decomposer processes. While phenolic characteristics of aboveground plant biomass are well-known, the fate of litter phenolics and their regulatory effects on belowground decomposition remain unclear. We conducted a two-year decomposition experiment distributing litterbags of spruce, pine, and bilberry along a gradient from mesic spruce-dominated to xeric pine-dominated forests. Litter material was analysed for mass loss, low molecular weight phenolic compounds, condensed tannins, fungal biomass, and fungal community composition (using DNA metabarcoding). Bilberry litter initially decayed more rapidly than the conifer litter, but the remaining mass of bilberry litter was the same as for pine and higher than that of spruce litter after two years. The concentration and composition of phenolic compounds decreased with time, with mainly MeOH-insoluble condensed tannins remaining at the end of the experiment. Correspondingly, fungal biomass increased in the first year, while all litter types underwent rapid changes in fungal community composition. The species-specific pattern of temporal change in mass loss, as well as in the synchronic shift in composition of phenolic compounds and fungal community, give new insights in the importance of litter quality for the decomposition process.

Cascade disassembling of spent coffee grounds into phenols, lignin and fermentable sugars en route to a green active packaging

Coffee is one of the most popular beverages worldwide, whose consumption generates spent coffee grounds (SCGs) as one of the major by-products. A new biorefinery flowchart aimed at the integral valorization of SCGs in view of the possible implementation of a sustainable active packaging is proposed in this work. The cascade approach started with a delipidization step to get coffee oil (13.0 g/100 g SCGs). Then, a hydroalcoholic extraction followed by a treatment with a deep eutectic solvent (composed of choline chloride and lactic acid) allowed to recover low molecular weight phenolic compounds (9.6 g/100 g SCGs) and lignin (6.2 g/100 g SCGs), respectively. Both fractions were found to display promising antioxidant properties in chemical assays. The residual solid material was then submitted to saccharification through a statistical approach, enabling the optimization of the enzymatic cocktail needed to address biomass structural and compositional complexity. The process resulted in 57 % and 73 % saccharification yields for cellulose and hemicellulose respectively, corresponding to the recovery of 11.6 g of fermentable sugars per 100 g of SCGs, and led to a homogeneous residual solid (4.3 g/100 g SCGs) still endowed with antioxidant properties. Finally, the possible use of the inhibitory-free saccharification extract for the microbial production of polyhydroxybutyrate was demonstrated using a proper engineered Escherichia coli strain, achieving about 0.7 g/L of biopolymer (1.2 g/100 g SCGs). Overall, the combination of the sequential processes applied in this work allowed to recover functional compounds accounting for ca. 45 % w/w of the starting biomass, paving the way to the development of a coffee-biorefinery aimed at the designing of fully biobased materials composed of polyhydroxyalkanoates and active additives, i.e. phenols and lignin.

Exploring the Potential of Vine Shoots as a Source of Valuable Extracts and Stable Lignin Nanoparticles for Multiple Applications.

Large amounts of vine shoots are generated every year during vine pruning. This residue still presents many of the compounds found in the original plant, including low molecular weight phenolic compounds and structural compounds such as cellulose, hemicellulose, and lignin. For wine-producing regions, the challenge is to develop alternatives that will increase the value of this residue. This work proposes the full valorization of vine shoots, focusing on the extraction of lignin by mild acidolysis for the preparation of nanoparticles. The effect of the pretreatment solvents (ethanol/toluene, E/T, and water/ethanol, W/E), on the chemical and structural features of lignin, was evaluated. The chemical analysis suggests similar composition and structure regardless of the pretreatment solvent, although lignin isolated after pretreatment of biomass with E/T showed a higher content of proanthocyanidins (11%) compared with W/E (5%). Lignin nanoparticles (LNPs) presented an average size ranging from 130-200 nm and showed good stability for 30 days. Lignin and LNPs showed excellent antioxidant properties (half maximal inhibitory concentration, IC50 0.016-0.031 mg/mL) when compared to commercial antioxidants. In addition, extracts resulting from biomass pretreatment showed antioxidant activity, with W/E presenting a lower IC50 (0.170 mg/mL) than E/T (0.270 mg/mL), correlated with the higher polyphenol content of W/E, with (+)-catechin and (-)-epicatechin being the main compounds detected. Overall, this work shows that the pre-treatment of vine shoots with green solvents can yield (i) the production of high-purity lignin samples with antioxidant properties and (ii) phenolic-rich extracts, promoting the integral reuse of this byproduct and contributing to sustainability.

Improvement of cupcake technology with the addition of dried beet pomace

The object is de-sugared beet pomace, which contains a large amount of dietary fiber in its composition, as well as the technology of cupcakes with its addition. The task of enriching cupcakes with useful substances is tackled. A production technique of dried powdered beet pomace has been substantiated, which is characterized by low-temperature concentration modes in the rotary evaporator and post-drying in the roller IR dryer, which could contribute to the preservation of physiologically functional ingredients. The rheological characteristics of concentrated beet pomace in the rotary evaporator in the temperature range of 65–75 °C were determined. The established indicators revealed a tendency to reduce the effective viscosity depending on the temperature in the range of 42 to 27 Pa·s. For the speed of the rotary evaporator agitator of 200–300 min–1, the maximum level of effective viscosity of beet pomace of 3–5 Pa·s was established. Studies of the rheological characteristics of the dough with the introduction of dried beet pomace have made it possible to establish an increase in its elastic-viscous properties with an increase in the amount of additive. The highest indicator of effective viscosity ηef (Pa∙s) of the studied dough samples for cupcakes with the addition of an additive of 10 % is 347; 15 % – 384; 20 % – 442; and control – 287, respectively. The compression of the crumb of finished cupcakes was also determined, which increases by 10.2–22.4 % with an increase in the amount of beet pomace powder. The organoleptic and physical-chemical indicators of the quality of cupcakes revealed the optimal amount of application of dried beet pomace – 15 %. The selected sample contains physiologically functional ingredients, namely dietary fiber, low molecular weight phenolic compounds, minerals. The technology can be introduced into the confectionery industry

Deep eutectic solvent pretreatment of biomass: Influence of hydrogen bond donor and temperature on lignin extraction with high β-O-4 content

Recovering lignin with high β-O-4 content is of prime interest for further high yield depolymerization in low molecular weight phenolic compounds. Pretreatment of lignocellulosic biomass with deep eutectic solvents (DES) was studied to extract this type of tailored lignin from softwood and brewer’s spent grains. In this work, choline chloride (ChCl) based DES with two different hydrogen bond donors (HBD) (lactic acid (LA) and Glycerol (Gly)), were investigated at mild temperatures (60 and 80 °C). The influence of DES pretreatment on extracted lignin molecular weight and structural characteristics was analysed. The acidity and density of DES were proved to affect lignin extraction yield and its features. The lignin characteristics (type of interunits, accessibility) were shown to impact their ability to be recovered. Acidic-DES ChCl:LA at 80 °C with woody biomass gave promising results with 78% of lignin extracted exclusively composed of G units with 61% of β-O-4 linkages with narrow molecular weights distribution.

Sustainable production of low molecular weight phenolic compounds from Belgian Brewers' spent grain

Brewers' spent grain (BSG) is a brewery co-product rich in phenolic compounds which only within Europe, 3-4Mt is generated annually. This study aims to sustainably isolate low-molecular-weight phenolic compounds from Belgian BSG using a microwave-assisted method (MW). Two types of BSG (from light and red malted barley grains) were subjected to MW at 600 and 800 W for 5, 15 and 30 min. MW showed a significant and positive effect on the release of 4-vinylguaiacol, a bioactive compound derived from the thermal decarboxylation of ferulic acid. The amounts of 4-vinylguaiacol in the extracts increased by about 80% after 30 min of MW despite the power applied. In the same time interval, total phenolic contents (TPC) increased of about 70% for light and 60% for red BSG. The highest TPC (13.23 mg/gDM) was obtained at 30 min and 600 W. This sustainable method could help add value to BSG by improving the extractability of bioactive phenolics.

Environment rather than provenance explains levels of foliar phenolics in European beech (Fagus sylvatica L.) seedlings

With progressive climate change, the chemical defense in European beech (Fagus sylvatica L.) is likely to change, which might impact its fitness and ability to establish beyond its current northern distribution limit. We studied the phenolic defense in six beech provenances grown in three common gardens in Norway the two first years after planting.We analyzed low molecular weight phenolic compounds by HPLC and condensed tannins by the acid-butanol assay. Sampling year explained most of the variance in phenolic defense, followed by environment (growing location), while the genetic background (provenance) showed the least explanatory power. After the first year in the field, the northernmost growing location had about 70% higher concentration of low molecular weight phenolics than the southern growing locations. The concentrations of condensed tannins, however, were lowest in the north. The mean concentration of total low molecular weight phenolics was twice as high after the first year compared to the second year. After the second year, the differences between the growing locations in many cases disappeared. The differences between the growing locations are probably caused by differences in temperature and soil fertility, while we attribute the decrease in low molecular weight phenols from the first to the second year to decreased water and nutrient stress, as well as aging. Our results suggest that intraspecific variations in concentration and composition of phenolic compounds in beech are caused by differences in the environment to a greater extent than the genetic background, which may indicate fast changes in chemical defense with climate change.

Bioaccessibility of cashew nut kernel flour compounds released after simulated in vitro human gastrointestinal digestion

Cashew nuts are mainly consumed as a roasted and salted snack. Lately, the industry has gained interest in broken kernels because of their added value. In this study, defatted cashew nut flour (DCF) underwent simulated gastrointestinal digestion to obtain a soluble (CDs) and an insoluble (CDi) digested fraction. These fractions, which resulted from the digestion of a complex matrix, were evaluated for antioxidant capacity of bioaccessible compounds (present on the soluble digested fraction, CDs) and their potential prebiotic effect, considering that the insoluble digested fraction (CDi) could be fermented by the microbiota in the gut. The DCF had a high protein content (40.74%), being nutritionally characterized as a balanced source of amino acids, with a predominance of aromatic amino acids (phenylalanine and tyrosine), threonine and histidine. The digested DCF presented 76.90% of the soluble components of low molecular weight (0.1–2 kDa), which is typical of antioxidant peptides. The soluble digested fraction (CDs) significantly increased the antioxidant capacity in relation to flour in the ORAC and ABTS assays and the aqueous extract presented the highest values (526.0 and 76.64 as µmol Trolox Eq./g sample, respectively). The CDs protected 29.03% of the supercoiled DNA band and ratified the potential antioxidant capacity after GID in a physiological assay. In addition, the insoluble digested fraction showed a potential prebiotic effect for Bifdobacterium lactis BB-12. Finally, simulated gastrointestinal digestion improves the bioaccessibility of CDF antioxidant compounds as a complex matrix, containing low molecular weight peptides and phenolic compounds, which become more available to react with reactive oxygen species (ROS). In addition, the potential prebiotic effect of defatted cashew nut flour has yielded a promising solution for the total reuse of broken cashew nut kernel as a functional food ingredient.

Acid Treatment Enhances the Antioxidant Activity of Enzymatically Synthesized Phenolic Polymers.

Phenolic polymers produced by enzymatic oxidation under biomimetic and eco-friendly reaction conditions are usually endowed with potent antioxidant properties. These properties, coupled with the higher biocompatibility, stability and processability compared to low-molecular weight phenolic compounds, open important perspectives for various applications. Herein, we report the marked boosting effect of acid treatment on the antioxidant properties of a series of polymers obtained by peroxidase-catalyzed oxidation of natural phenolic compounds. Both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated a remarkable increase in the antioxidant properties for most phenolic polymers further to the acid treatment. In particular, up to a ca. 60% decrease in the EC50 value in the DPPH assay and a 5-fold increase in the Trolox equivalents were observed. Nitric oxide- and superoxide-scavenging assays also indicated highly specific boosting effects of the acid treatment. Spectroscopic evidence suggested, in most cases, that the occurrence of structural modifications induced by the acid treatment led to more extended π-electron-conjugated species endowed with more efficient electron transfer properties. These results open new perspectives toward the design of new bioinspired antioxidants for application in food, biomedicine and material sciences.

Application of Functional Data Analysis and FTIR-ATR Spectroscopy to Discriminate Wine Spirits Ageing Technologies

Fourier transform infrared spectroscopy (FTIR) with Attenuated Total Reflection (ATR) combined with functional data analysis (FDA) was applied to differentiate aged wine spirits according to the ageing technology (traditional using 250 L wooden barrels versus alternative using micro-oxygenation and wood staves applied in 1000 L stainless steel tanks), the wood species used (chestnut and oak), and the ageing time (6, 12, and 18 months). For this purpose, several features of the wine spirits were examined: chromatic characteristics resulting from the CIELab method, total phenolic index, concentrations of furfural, ellagic acid, vanillin, and coniferaldehyde, and total content of low molecular weight phenolic compounds determined by HPLC. FDA applied to spectral data highlighted the differentiation between all groups of samples, confirming the differentiation observed with the analytical parameters measured. All samples in the test set were differentiated and correctly assigned to the aged wine spirits by FDA. The FTIR-ATR spectroscopy combined with FDA is a powerful methodology to discriminate wine spirits resulting from different ageing technologies.

Fertilization of Norway spruce forest with wood ash and nitrogen affected both tree growth and composition of chemical defence

AbstractWe fertilized a Norway spruce (Picea abies (L.) Karst.) stand on rich mineral soil with 3 t ha−1 of wood ash (ASH), 150 kg ha−1 of nitrogen (N) or a combination of wood ash and nitrogen (ASH + N), in addition to unfertilized control plots. After five growing seasons, we remeasured the trees and took core samples. Current- and previous-year needles were sampled and analyzed for total nitrogen and carbon, low-molecular weight phenolics and condensed tannins. Annual volume increment and standing volume were significantly higher in the ASH + N treatment than in control plots after 5 years. N gave a significant positive effect on basal area growth in the third year, after which the effect diminished. The ASH + N treated trees, on the other hand, showed an increasing basal area growth trend throughout the period. ASH reduced the total concentration of low-molecular weight phenolic compounds significantly in current-year needles. Phenolic acids increased under both ASH and ASH + N, while flavonoids decreased significantly under the same treatments compared to N. By including annual growth rate before fertilization in the analyses, the effect of N-treatment on flavonoids was positive only in trees with higher growth rates, and in those trees the concentration was higher than in both ASH-treated plots and controls. An acetophenone, constituting more than half of the total low-molecular weight phenolics concentration, was strongly reduced under all fertilization treatments. These results demonstrate that in addition to effects on tree growth, fertilization of the forest floor also has a strong influence on other metabolic processes of trees, with potential implications for ecosystem functioning.

Profile and concentration of the low molecular weight organic acids and phenolic compounds created by two-year-old Acer platanoides seedlings growing under different As forms

Two-year-old seedlings of Acer platanoides were cultivated during a three-month hydroponic experiment in modified Knop solution enriched with inorganic (As(III), As(V)) and organic (dimethylarsinic acid - DMA) arsenic forms at 0.06 mM, 0.6 mM and their combinations. The profile and content of low molecular weight organic acids (LMWOAs) and phenolic compounds were also determined in the rhizosphere, roots and leaves. Arsenic (As) treatment caused an elevated creation of the above mentioned metabolites, which was higher in leaves than in the rhizosphere or roots, and their overall content was correlated with the concentration of As in A. platanoides organs. The addition of all As forms strongly induced the exudation of citric and oxalic acids into the rhizosphere, while malonic, acetic, citric and malic acids were formed in the roots. The most differential profile of roots was confirmed for As(V) 0.06 mM (4-hydroxybenzoic (4-HBA), syringic, 2,5 dihydroxybenzoic (2,5-DHBA), caffeic, chlorogenic, ferulic, p-coumaric and sinapic acids and catechin). The obtained results indicate that the presence of particular As forms has a significant impact on the content and profile of exuded and created LMWOAs and phenolic compounds, and can also have a decisive influence on the activation of appropriate detoxification mechanisms.

PAH destruction in nitrogen deficient conditions by Pseudomonas putida strain BS3701

Two-year-old seedlings of Acer platanoides were cultivated during a three-month hydroponic experiment in modified Knop solution enriched with inorganic (As(III), As(V)) and organic (dimethylarsinic acid - DMA) arsenic forms at 0.06 mM, 0.6 mM and their combinations. The profile and content of low molecular weight organic acids (LMWOAs) and phenolic compounds were also determined in the rhizosphere, roots and leaves. Arsenic (As) treatment caused an elevated creation of the above mentioned metabolites, which was higher in leaves than in the rhizosphere or roots, and their overall content was correlated with the concentration of As in A. platanoides organs. The addition of all As forms strongly induced the exudation of citric and oxalic acids into the rhizosphere, while malonic, acetic, citric and malic acids were formed in the roots. The most differential profile of roots was confirmed for As(V) 0.06 mM (4-hydroxybenzoic (4-HBA), syringic, 2,5 dihydroxybenzoic (2,5-DHBA), caffeic, chlorogenic, ferulic, p-coumaric and sinapic acids and catechin). The obtained results indicate that the presence of particular As forms has a significant impact on the content and profile of exuded and created LMWOAs and phenolic compounds, and can also have a decisive influence on the activation of appropriate detoxification mechanisms.

Using the CODIT model to explain secondary metabolites of xylem in defence systems of temperate trees against decay fungi.

In trees, secondary metabolites (SMs) are essential for determining the effectiveness of defence systems against fungi and why defences are sometimes breached. Using the CODIT model (Compartmentalization of Damage/Dysfunction in Trees), we explain defence processes at the cellular level. CODIT is a highly compartmented defence system that relies on the signalling, synthesis and transport of defence compounds through a three-dimensional lattice of parenchyma against the spread of decay fungi in xylem. The model conceptualizes 'walls' that are pre-formed, formed during and formed after wounding events. For sapwood, SMs range in molecular size, which directly affects performance and the response times in which they can be produced. When triggered, high-molecular weight SMs such as suberin and lignin are synthesized slowly (phytoalexins), but can also be in place at the time of wounding (phytoanticipins). In contrast, low-molecular weight phenolic compounds such as flavonoids can be manufactured de novo (phytoalexins) rapidly in response to fungal colonization. De novo production of SMs can be regulated in response to fungal pathogenicity levels. The protective nature of heartwood is partly based on the level of accumulated antimicrobial SMs (phytoanticipins) during the transitionary stage into a normally dead substance. Effectiveness against fungal colonization in heartwood is largely determined by the genetics of the host. Here we review recent advances in our understanding of the role of SMs in trees in the context of CODIT, with emphasis on the relationship between defence, carbohydrate availability and the hydraulic system.We also raise the limitations of the CODIT model and suggest its modification, encompassing other defence theory concepts. We envisage the development of a new defence system that is modular based and incorporates all components (and organs) of the tree from micro- to macro-scales.

Phenolic profile and colour acquired by the wine spirit in the beginning of ageing: Alternative technology using micro-oxygenation vs traditional technology

Alternative technologies have been extensively investigated towards a more sustainable ageing of red wine, but few studies were made on wine spirits. Moreover, the effect of micro-oxygenation on wine spirits’ ageing is still unknown. This work examined the effect of micro-oxygenation and wood staves applied in 1000 L stainless steel tanks versus 250 L wooden barrels on the phenolic composition and chromatic characteristics acquired by the wine spirit over the first six months of ageing. Two different kinds of wood, Limousin oak and chestnut, were used. Significantly higher total phenolic content and individual contents of low molecular weight phenolic compounds (syringic acid, ellagic acid, vanillin, syringaldehyde, coniferaldehyde, sinapaldehyde and umbelliferone) were obtained with micro-oxygenation and staves than with barrels, for both kinds of wood. Accordingly, greater colour evolution (lower lightness, higher saturation and higher intensities of red, yellow and brown hues) was achieved in the former. These results were ascribed to a faster extraction and its balance with several phenomena involving the wood-derived compounds in the specific environment created by the direct supply of oxygen. A synergistic effect between the alternative technology and the chestnut wood was also observed.

Hydrotreatment of pyrolytic lignins to aromatics and phenolics using heterogeneous catalysts

The pyrolysis of lignocellulosic biomass generates a liquid product, known as pyrolysis oil, that can be further processed into biofuels and value-added chemicals. During pyrolysis, cellulose and hemicelulose fractions are converted into a range of water-soluble sugar derivatives, for which several valorisation strategies exist. On the other hand, lignin is broken down into so-called pyrolytic lignin, a water-insoluble complex mixture of aromatic oligomers that requires different upgrading strategies than the sugar rich fraction. Here, we report an experimental study on the valorisation of pyrolytic lignin via catalytic hydrotreatment in the absence of an external solvent. A variety of carbon-supported noble-metal heterogeneous catalysts were tested (Ru/C, Pd/C, Pt/C and Rh/C), as well as conventional hydrotreatment catalysts (sulphided NiMo/Al2O3 and CoMo/Al2O3) to obtain valuable low molecular weight aromatic and phenolic compounds. Overall, depolymerized liquids were obtained with organic yields of up to 63 wt%. Pd/C was shown to be the best catalyst, yielding 59 wt% of monomers based on the organic product (i.e. 33 wt% based on pyrolytic lignin intake). While noble metal catalysts favored higher monomer yields, though with some over-reduction of aromatic rings to saturated hydrocarbons, sulphided catalysts were more efficient in deoxygenation and aromatization reactions, but yielded less monomers. The hydrocracking efficiency was shown to be strongly dependent on the reaction temperature. Based on the experimental data, a global reaction network is proposed. The high monomer yields reveal the potential of catalytic hydrotreatment for the upgrading of pyrolytic lignin into valuable phenolics and aromatics.

Simultaneous identification of low-molecular weight phenolic and nitrogen compounds in craft beers by HPLC-ESI-MS/MS

Phenolic and nitrogenous compounds from different styles craft beers were identified by high performance liquid chromatography and mass spectrometry in order to stratify beer samples according to their style. For this, an exploratory assessment relying on Linear Discriminant Analysis was performed. Fifty-seven phenolic compounds were reported and twelve of them were found for the first time in beer: benzoic acids, 2,4-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, dimethoxybenzoic acid; phenolic acid conjugates, 3-p-coumaroylquinic acid, 4-p-coumaroylquinic acid, 3-feruloylquinic acid, 4-feruloylquinic acid, 5-feruloylquinic acid; flavonoids, taxifolin hexoside, quercetin dihexoside, apigenin-6,8-dipentoside, and isofraxidin hexoside. Additionally, 11 nitrogenous compounds belonging to the phenolamide class were found. Two discriminant functions were generated and allowed a satisfactory separation among all beer styles. 3-Caffeoylquinic acid, 3-p-coumaroylquinic acid, 4-p-coumaroylquinic acid, 5-caffeoylquinic acid, coumaric acid, kaempferol-3-O-rutinoside, proanthocyanidin B dimer III and proanthocyanidin B dimer V were the compounds that showed the highest capacity of discriminate the beer styles (IPA, Lager and Weiss).